Overweight and obesity

Wider determinants of health

There are many factors, known as the 'wider determinants of health', that influence our health. These determinants are the ‘causes of the causes’ and include the social, environmental, structural, economic, cultural, biomedical, commercial and digital environments in which we live, work, play and age (Department of Health 2021).

These broad contextual factors play an integral role in determining the health of a community and are the basis for systemic inequity and inequality in society (Department of Health 2021). Individuals often have limited or no control over many of these determinants as they are shaped outside their area of influence.

The National Obesity Strategy 2022–2032 and the National Preventive Health Strategy 2021–2030 acknowledge that these wider determinants of health play a major role in influencing healthy weight and healthy living (Commonwealth of Australia 2022).

Obesogenic environments

The root causes of overweight and obesity are varied and complex, with many factors lying outside the control of the individual. 

Overweight and obesity mainly occurs when there is a sustained energy imbalance, where too much energy is consumed through food and drink, and not enough is expended through physical activity. However, many other factors also influence overweight and obesity, including:

• Genetics and physiology, which influence how the body regulates body composition and weight through differences in metabolism, appetite, satiety signalling and fat storage. These factors can also predispose some people to gain weight more easily or have greater difficulty losing and maintaining weight loss (Lesley and Campbell 2017).
• Health inequalities, which can shape exposure to obesity risk through social and structural disadvantage. Obesity is unfairly distributed with those living in socioeconomically disadvantaged or remote areas facing poorer access to healthy foods, safe environments for physical activity and health services. Inequalities in obesity prevalence associated with ethnicity has also been shown, due to factors such as disadvantage, discrimination or environments that are not supportive of culturally appropriate and healthy diets (Capoccia et al. 2025).
• Environmental factors, which impact the availability, affordability and accessibility of healthy foods as well as access to physical activity. These in turn influence dietary behaviours and physical activity participation. Having access to health–promoting built environments are also associated with social structure, where disadvantaged areas have limited access to healthy food options, while fast food outlets are more prevalent (Capoccia et al. 2025).
• Commercial determinants, which are the private sector activities that influence people’s health and exposure to health risk factors, such as obesity. Targeted advertising (including to children) and retail strategies, such as product placement and price promotions, can shape consumer preferences and attitudes by enhancing the desirability, acceptability and availability of unhealthy food options. This affects consumption patterns that can increase the risk of obesity. These targeted marketing disproportionately affects lower socioeconomic neighbourhood, further exacerbating health inequities (Chung et al. 2022).

Together, these factors interact to create obesogenic environments, used to describe an environment that promotes obesity (Swinburn et al. 1999), where biological susceptibility is amplified by social, environmental and commercial pressure. 

These factors are influenced by laws and policies, industry, economic imperatives, and society. They shape and affect an individual’s energy balance, by encouraging or inhibiting healthy dietary and physical activity patterns (Espinel and King 2009), which in turn, influences a person’s body weight making overweight and obesity more likely at a population level. 

Diagram 1: The obesogenic environment

Food and nutrition

The total amount of food that your body requires depends on your age, sex, body size, level of physical activity and whether you are pregnant or breastfeeding. Maintaining adequate nutrition is important across all life stages to support overall physical and mental health and wellbeing. 

Visit eatforhealth.gov.au to calculate your individual energy requirements.

The Australian Guide to Healthy Eating is a food selection guide that visually represents the proportion of the 5 food groups recommended for consumption each day. Following these recommendations and limiting the number of energy-dense, nutrient-poor discretionary foods and drinks is the best way to maintain a healthy weight. For the majority of Australians, their diets do not reflect these recommendations. Recent data from the ABS’s 2022 NHS, show that most children aged 2–17 (96%) and adults aged 18 and over (96%) do not meet the recommended daily serves of fruit and vegetables (ABS 2023a, 2023b).

Dietary behaviour and patterns are not solely driven by individual choice. The ability to have a nutritious diet is greatly influenced by the environment and food systems. These factors include (Swinburn et al. 1999):

• changes in global food systems over time, where food has become more processed, portion sizes are larger, and where convenience foods are more affordable than healthier alternatives
• effective marketing techniques and product placements to promote the sale of unhealthy foods
• being able to access adequate and nutritious foods (which can include cost, availability, accessibility and location).

For more information on dietary behaviours and patterns, see Diet.

Physical activity

The human body expends energy in 3 ways:

• basal metabolism (the energy used to keep the body functioning at rest, such as breathing and blood circulation)
• thermic processes (the energy taken to digest and absorb food)
• physical activity (the energy used to move around).

Being physically active throughout life helps to promote health and wellbeing and prevent chronic disease (AIHW 2018b).

Too much sedentary behaviour (sitting or lying down, except when sleeping) is also associated with poorer health outcomes (Martin 2011; Straker et al. 2010; Tremblay et al. 2010). Breaking up prolonged sedentary activities can promote more healthful effects in individuals with high levels of sedentary behaviour (Duvivier et al. 2013). The 24-hour movement guidelines for all Australians recommend the type, duration, intensity and frequency of physical activity, and practices for sedentary behaviour, for people during different life stages.

Being able to participate in adequate levels of physical activity is affected by individual, social, economic and structural factors (Department of Health 2021). Where an individual lives, their level of income, their health status and whether they can access safe environments and spaces all contribute to their ability to participate in physical activity.

For more information on physical activity participation, see Physical activity.

Physiological causes of overweight and obesity

Overweight and obesity can also be influenced by a range of physiological processes that regulate energy intake, energy expenditure and fat storage. These include differences in metabolic rate, hormonal regulation of appetite and satiety, genetic susceptibility, and the way the body stores and distributes fat.

Physiological changes across the life course, such as growth, ageing and hormonal transitions, can also affect body weight. Some illnesses and medications may further alter appetite, metabolism or physical capacity.

These biological factors interact with environmental and social influences and operate largely outside individual control, highlighting that overweight and obesity is a complex health condition rather than being the result of personal choice alone (Rubino et al. 2025).